--- ckan/ckan/model/__init__.py	2021-02-16 14:47:06.168327441 +0100
+++ ckan/ckan/model/__init__.py	2021-02-16 14:48:00.740780218 +0100
@@ -266,7 +266,7 @@
         self.reset_alembic_output()
         alembic_config = AlembicConfig(self._alembic_ini)
         alembic_config.set_main_option(
-            "sqlalchemy.url", str(self.metadata.bind.url)
+            "sqlalchemy.url", str(self.metadata.bind.url).replace('%', '%%')
         )
         try:
             sqlalchemy_migrate_version = self.metadata.bind.execute(